This is a continuation-in-part of application Ser. No. 239,517, filed on Sept. 1, 1988.
The present invention relates in general to packaging components and methods, and more particularly to an improved metallized package component and methods for forming the same.
In the prior art, various methods have been proposed for techniques of providing heat to thermoplastic polymeric film materials for forming packaging components, whether by various vacuum techniques, and with or without plug assist. Some of these techniques are set forth in the above identified parent patent application.
Two such forms of heat have been utilized for thermal forming of polymeric sheet materials and include (1) radiant heat, and (2) contact heat. Radiant heaters have been used for the most part on fixed speed, dedicated thermoforming machines. Contact heaters have had certain advantages over radiant heaters, such as being less complex in structure, and accordingly less costly to purchase and maintain. Such contact heaters have been used in a number of fixed or variable speed thermoforming machines, such as non-dedicated, form and seal machines and other machines.
In addition to the above advantages of reduced expense in purchase and maintenance, contact heaters have been less expensive to operate. In particular, contact heaters convert energy more efficiently than do radiant heaters. In addition, contact heaters have the further advantage of requiring less skilled personnel to achieve operation in a satisfactory fashion. However, the use of contact heaters into thermoforming of polymeric sheet materials has been relatively limited, and in particular has been limited to the low temperature heating of films. Once a film material has been subjected to the desirably higher temperatures which are more suitable for thermoforming, and especially the thermoforming of more precise shapes necessary for more sophisticated packaging, the softened polymeric sheet becomes tacky and tends to adhere to the surface of the contact heater. This phenomenon occurs because, as the temperature increases, the coefficient of friction of the surface of the thermoplastic sheet which is being transported past and in contact with the contact heater also increases. Thus, such increase in the coefficient of friction, and especially above the glass transition temperature of the polymeric film material has confined the use of such contact heaters to relatively low-temperature thermoforming, or cold phase thermoforming methods.
In the prior art, proposals have been made for various types of metallic packaging materials. However, with such metallic materials it has been necessary to utilize metallic coating on both sides of a film, in part because of the cosmetic necessity to cover completely both surfaces of laminated polymeric materials, which have had a "milky" or "cloudy" appearance. This cloudy appearing of film laminates has been caused by the necessity for utilizing different types of materials forming the different layers of thermoplastic materials, in order to accomplish various packaging functions, such as resistance to gaseous diffusion, thermoformability, durability, etc. Attempts to solve these problems have been somewhat less than successful.
In view of the difficulties and deficiencies of prior art methods of thermoforming polymeric film materials, it is a material object of the improved metallized package components and methods for producing the same of the present invention to alleviate such difficulties and deficiencies experienced with such prior art methods.